Effects of a grazing fish, Plecoglossus altivelis (Osmeridae), on the taxonomic composition of freshwater benthic algal assemblages

Author(s):  
Shin-ichiro Abe ◽  
Kazuo Uchida ◽  
Tamotsu Nagumo ◽  
Teru Ioriya ◽  
Jiro Tanaka
2017 ◽  
Vol 32 (1) ◽  
pp. 11
Author(s):  
IVONNE LUNA ORTEGA ◽  
VICENCIO DE LA CRUZ FRANCISCO

Las macroalgas son abundantes en el arrecife Oro Verde, Veracruz pero, hasta ahora, se desconocía su riqueza taxonómica, y se presume que presentan asentamientos en los corales escleractinios hermatípicos. Por ello el presente trabajo investigó qué especies de corales presentaron colonizaciones algales; además, se determinó la composición taxonómica y la similitud de los ensambles de macroalgas entre las especies de corales escleractinios. Se establecieron diez puntos de muestreo de manera sistemática en el arrecife; en cada lugar de estudio se colocó un transecto de banda de 50 x 2 m para localizar y recolectar macroalgas en superficies muertas de corales escleractinios. La frecuencia de aparición de las algas se estimó con base en el total de corales estudiados, así como para cada especie coral. Para explicar similitudes y diferencias significativas de la composición de ensamblajes macroalgales entre especies de corales se aplicaron análisis de similitud y ordenación. Los corales escleractinios con ensambles de algas fueron Siderastrea siderea, Montastraea cavernosa, Pseudodiploria strigosa, Colpophylia natans, Stephanocoenia intersepta, Porites astreoides, Orbicella annularis, Orbicella faveolata. De un total de 100 colonias coralinas revisadas se determinaron 32 especies de macroalgas, las cuales están representadas en tres divisiones, 10 órdenes y 15 familias. Las macroalgas corticadas, foliosas corticadas y filamentosas fueron las más representadas en especies. Las algas de mayor frecuencia sobre los corales masivos fueron Laurencia obtusa, Amphiroa rigida y Caulerpa chemnitzia. Los corales masivos con mayor número de registros de algas fueron S. siderea (9 especies), M. cavernosa (19) y P. strigosa (17). Los ensambles algales en los corales masivos presentaron baja similitud, sin embargo no se detectaron grupos significativamente disimiles. Solamente S. siderea y M. cavernosa son ligeramente parecidos en la composición ficológica. Los resultados sugieren que los corales masivos del arrecife Oro Verde son vulnerables a la colonización de algas, pero es necesario indagar qué condiciones preceden al asentamiento algal.Macroalgal assemblages on dead surfaces of scleractinian corals (Anthozoa: Scleractinia) in the Oro Verde reef, Veracruz, MexicoBenthic macroalgae are abundant in the Oro Verde reef but their taxonomic richness was hitherto unknown and it is presumed to present settlements on the massive corals. For this reason, the present work investigated which species of massive corals show algal colonization. Also, their taxonomic composition was determined, and the similarity of the algal assemblages between species of scleractinian corals was measured. Ten sampling points were systematically established in the reef, where a transect band of 50 x 2 m at each site was placed to locate and collect algae fron the dead surfaces of scleractinian corals. The frequency of occurrence of algae species was estimated based on the total number of coral species studied, as well as on each coral species. Similarity and ordination analysis were applied in order to explain similarities and significant differences of the phycological composition among the coral species. Scleractinian corals with algal assemblages were: Siderastrea siderea, Montastraea cavernosa, Pseudodiploria strigosa, Colpophylia natans, Stephanocoenia intersepta, Porites astreoides, Orbicella annularis, Orbicella faveolata. Thirty-two species of algae were identified from a total of 100 revised coral colonies which are represented in 3 divisions, 10 orders and 15 families. The corticated, foliose corticated and filamentous macroalgae were the most represented species. The most frequent algae on massive corals were Laurencia obtusa, Amphiroa rigida and Caulerpa chemnitzia. Massive corals with higher algal records were S. siderea (9 species), M. cavernosa (19 species) and P. strigosa (17 species). The algal assemblages on the massive corals presented low similarity. However, no significant dissimilar groups were detected. Only S. siderea and M. cavernosa are relatively similar in phycological composition. The results suggest that the massive corals of the Oro Verde reef are vulnerable to the colonization of algae, but it is necessary to investigate the conditions preceding algal settlement.


2011 ◽  
Vol 71 (3) ◽  
pp. 587-600 ◽  
Author(s):  
M. Teixeira de Oliveira ◽  
O. Rocha ◽  
AC. Peret

The limnological features and the phytoplankton community of the Cachoeira Dourada reservoir were analyzed in December 2006, May 2007 and November 2007. Temporal changes in the taxonomic composition, density, diversity and dominance of species were analyzed in relation to climatic factors and the physical and chemical characteristics of the water. A positive correlation was found between some of the physical and chemical variables and the phytoplankton community. According to the CCA, variables such as the extent of the euphotic zone, temperature, pH, nitrogen and phosphorus concentrations directly affected the phytoplankton dynamics. Organisms belonging to the class Cyanophyceae were the most representative in all the sampling periods, comprising the functional groups K, S1, M and H. Hydrodynamics and seasonal fluctuations of environmental factors were the driving forces determining the composition and abundance of the algal assemblages. Despite the prevalence of Cyanobacteria, the reservoir is still oligotrophic. The absence of blooms and the relatively low population abundances indicated that the quality of the reservoir's water still lies within the limits required for its multiples uses.


2014 ◽  
Vol 65 (9) ◽  
pp. 784 ◽  
Author(s):  
E. T. Chester ◽  
B. J. Robson

When intermittent streams flow, benthic algae develop from both colonising propagules and regrowing dried biofilm. We aimed to determine whether colonisation processes influence algal densities and taxonomic composition beyond the period immediately following commencement of winter flows, and whether regulation modifies those processes, in the Victoria Range, Australia. Stones were placed in two unregulated streams, and upstream and downstream of weirs in three regulated streams, after dry biofilm was removed. Epilithic algae on treatment and control stones were collected after winter flows (12 weeks). Treatment effects were still apparent in one (unregulated) stream, but not in the other streams. Algal assemblages and densities upstream and downstream of weirs differed, but there was no systematic pattern among streams. In intermittent headwater streams, recolonisation processes may influence algal assemblages until spring; but in most streams, the duration of influence will be shorter, depending on the assemblage composition in regrowth and refuges, which is also shaped by conditions during the previous flow season. If the effects of regulation depend on how idiosyncratic flow regimes and assemblage compositions influence recolonisation, they may be difficult to predict. Similarly, recovery trajectories for stream communities after drought will differ among streams, depending on whether biofilm can develop during potentially short seasonal flows.


Author(s):  
M. A. Gondal ◽  
S. Iqbal ◽  
U. Atique ◽  
N. U. Saher ◽  
N. A. Qureshi ◽  
...  

Abstract The primary objective of this study was to investigate the seasonal fish and crustacean variations concerning taxonomic composition, species richness, and diversity in sandy beach habitat. For this purpose, we investigated the Sonmiani Hor lagoon area during four distinct seasons, i.e., northeast (NE) monsoon, pre-monsoon, south-west (SW) monsoon, and post-monsoon for one year. During each haul, the net was pulled about 100m along the beach in 0.5m depth. The results showed a strong linear correlation between the diversity index and equitability in fishes (r = 0.978). The diversity index was strong negatively correlated with the abundance and biomass (r = -0.978, -0.972, respectively). The physical attributes like sea surface water temperature and salinity showed a strong negative effect on species assemblages (r = -0.981 and -0.943, respectively). The mean air and water temperature illustrated approximately 3°C difference during NE and pre-monsoon seasons. However, salinity, pH, and electrical conductivity did not show any significant seasonal variabilities. Under the ecological indices, the fish species displayed higher diversity (H’ = 3.19) during SW monsoon, whereas the lowest diversity was observed during pre-monsoon (H’ = 1.58). The equitability and species richness, however, remained more noticeable during SW monsoon (J’ = 0.81). The total number of individuals of fish and crustaceans reached 4799 with 3813 fish individuals and 986 individuals of crustaceans. A total of 27 families of fish while five crustacean families comprising of 30 genera and 38 fish species while ten genera and 17 species of crustaceans were recorded. Liza subviridis displayed the highest abundance among the sampled fish species. In conclusion, fish species constituted a significant part of the coastal fauna in the study area. The seasonal variations displayed distinct variations in fish species composition and diversity.


2019 ◽  
pp. 105-115
Author(s):  
А.Ш. Хужахметова

Показана актуальность изучения экологической пластичности древесных растений в связи с необходимостью подбора адаптированного видового состава деревьев и кустарников для защитных лесных насаждений в условиях климатических изменений. Установлено, что экологическая пластичность и пределы толерантности растений связаны со свойством организмов адаптироваться к тому или иному диапазону факторов среды. В статье представлен таксономический состав орехоплодных культур коллекций ФНЦ агроэкологии РАН. Это шесть видов рода Juglans: J. regia, J. mandshurica, J. cinerea, J. rupestris, J. ailanthifolia, J. nigra и три вида рода Corylus: С. avellana L., С. аmericana W., сорта С. pontica C. Koch Президент, Футкурами, Черкесский2. Приведены сведения о положительном опыте культивирования Corylus avellana L. в плантационных насаждениях (1,6 га, посадка рядовая, схема размещения 55 м) в условиях южных черноземов. Цель исследований изучить экологическую пластичность орехоплодных кустарников коллекций ФНЦ агроэкологии РАН. На примере родового комплекса Corylus получены материалы по экологической пластичности орехоплодных кустарников в условиях каштановых (кадастр. 34:36:0000:14:0178), светлокаштановых почв (34:34:000000:122 34:34:060061:10). Установлены уровни изменчивости морфологических признаков ассимиляционного аппарата и плодов С. avellana L., сортов С. pontica C. Koch., которые согласуются с зимо и засухоустойчивостью. Кластерный анализ позволил выявить корреляцию признаков при 5 уровне значимости. Для целей защитного лесоразведения и озеленения засушливых районов рекомендованы Corylus avellana и Черкесский2 с выраженной вариабельностью морфологических признаков, которая указывает на их широкую экологическую валентность и адаптационные возможности в рассматриваемых условиях. The urgency of studying the ecological plasticity of woody plants in connection with the need to select an adapted species composition of trees and shrubs for protective forest plantations in the context of climate change is shown. It is established that the ecological plasticity and tolerance range of plants is associated with the ability of organisms to adapt to a particular range of environmental factors. The article presents the taxonomic composition of nut crops in the collections of FSC Agroecology RAS. Six species of Juglans: J. regia, J. mandshurica, J. cinerea, J. rupestris, J. ailanthifolia, J. nigra and three species of the genus Corylus: С. avellana L., С. аmericana W., varieties of C. pontica C. Koch the President, Futkurami, Circassian2. Data on positive experience of cultivation of Corylus avellana L. in plantation plantings (1,6 hectares, landing ordinary, the scheme of placement of 55 m) in the conditions of southern chernozems are given. The purpose of the research is to study the ecological plasticity of nutbearing shrubs of the collections of the Federal scientific center for Agroecology Russian Academy of Sciences. For example, a generic complex Corylus submissions received on the environmental plasticity of nut bushes in the conditions of brown (the cadaster nubmer 34:36:0000:14:0178), light chestnut soils (34:34:000000:122 34:34:060061:10). The levels of variability of morphological features of the assimilation apparatus and fruits of Corylus avellana L., С. pontica C. Koch varieties were established., which are consistent with winter and drought resistance. Cluster analysis revealed the correlation of features at 5 significance level. Corylus avellana and Circassian2 with a pronounced variability of morphological features, which indicates their broad ecological valence and adaptation capabilities in the conditions under consideration, are recommended for the purposes of protective afforestation and greening of dry areas.


2018 ◽  
Vol 0 (4) ◽  
pp. 54-56
Author(s):  
R. I. Sydorchuk ◽  
O. Y. Khomko ◽  
R. P. Knut ◽  
P. M. Volyanyuk ◽  
L. I. Sydorchuk ◽  
...  

2018 ◽  
Vol 52 (2) ◽  
pp. 519-534 ◽  
Author(s):  
V. E. Fedosov

Recent studies on Orthotrichoid mosses in Russia are summarized genus by genus. Orthotrichum furcatum Otnyukova is synonymized with Nyholmiella obtusifolia. Orthotrichum vittii is excluded from the Russian moss flora. Description of O. dagestanicum is amended. Fifty four currently recognized species from 9 genera of the Orthotrichaceae are presently known to occur in Russia; list of species with common synonyms and brief review of distribution in Russia is presented. Numerous problematic specimens with unresolved taxonomy were omitted for future. Revealed taxonomical inconsistencies in the genera Zygodon, Ulota, Lewinskya, Nyholmiella, Orthotrichum are briefly discussed. Main regularities of spatial differentiation of the family Orthotrichaceae in Russia are considered. Recently presented novelties contribute to the certain biogeographic pattern, indicating three different centers of diversity of the family, changing along longitudinal gradient. Unlike European one, continental Asian diversity of Orthotrichaceae is still poorly known, the Siberian specimens which were previously referred to European species in most cases were found to represent other, poorly known or undescribed species. North Pacific Region houses peculiar and poorly understood hot spot of diversity of Orthotrichoid mosses. Thus, these hot spots are obligatory to be sampled in course of revisions of particular groups, since they likely comprise under-recorded cryptic- or semi-cryptic species. Latitudinal gradient also contributes to the spatial differentiation of the revealed taxonomic composition of Orthotrichaceae.


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